1. Field of the Invention
The present invention relates to devices used to convert analog electrical signals to digital electrical signals.
2. Related Art
Analog-to-digital (A-D) converters are used in test and data acquisition instruments. State of the art A-D converters based on III-V semiconductors provide eight bit resolution at 2 GHz and three bit resolution at 8 GHz. State of the art silicon based A-D converters operate at 500 MHZ with seven bits of resolution. Because of the limited bandwidth and sampling rates of electronic A-D converters, some optical devices, have in some instances, been incorporated into A-D converters in an attempt to increase the bandwidth and sampling rate.
In U.S. Pat. No. 5,010,345, to Hamilton et al., an electro-optical A-D converter is disclosed which uses a series of separate lasers having different wavelengths as an optical carrier. It will be appreciated that it is difficult to synchronize the timing and amplitude of these laser beams and that the resulting jitter between the channels limits the sampling rate and amplitude resolution. Moreover, the number of channels such an electro-optical A-D converter can use appears to be limited to about ten. A device with more channels would have a higher bandwidth and sampling rate.